1. Field of the Invention
The present invention relates to a parallel link robot which uses a δ-type parallel link mechanism which is connected by ball joints and which positions an end effecter three-dimensionally.
2. Description of the Related Art
FIG. 6 is a perspective view of a parallel link robot in the related art. As shown in FIG. 6, the parallel link robot 100 of the related art mainly contains a base part 110, a movable part 120, and three link parts 200a to 200c which link the base part 110 and movable part 120. Note that, the movable part 120 is provided with a mounting member 190 of a not shown end effecter.
As can be seen from FIG. 6, the link part 200a includes a drive link 210a which extends from the base part 110 and two driven links 220a and 230a which extend from the movable part 120. Further, the base part 110 includes an actuator 130a which drives the drive link 210a. Note that, the other link parts 200b and 200c are similarly configured. By individually controlling the actuators 130a to 130c of these link parts 200a to 200c, it is possible to make the movable part 120 move by three degrees of freedom (first axis to third axis) and position it at a desired position.
In this regard, the drive link 210a and driven links 220a and 230a and the driven links 220a and 230a and movable part 120 are joined by ball joints which are comprised of balls and cups. In International Publication of Translated Version No. 2002-529258A, to increase the range of possible movement of the ball joints, the cups are made smaller than half spheres. In this case, the cups can be separated from the balls. Therefore, to avoid the cups from being separated from the balls, two facing cups have to be connected by springs.
However, even when providing such springs, if outside forces which are larger than the forces of the springs are applied, the balls of the ball joints may be detached from the cups. In particular, when a parallel link robot is used in the field of food, pharmaceuticals, cosmetics, etc., due to problems in sanitation, it is necessary to avoid separation of the ball joints. Further, for similar reasons, it is desirable to prevent wear debris which is produced from the ball joints from being dispersed.
Further, in general, a parallel link robot is required to operate at a high speed. To realize this, it is necessary to make the driven links and movable part as light as possible.
The present invention was made in consideration of such a situation and has as its object to provide a parallel link robot which is provided with difficult-to-separate ball joints and which is light weight and prevents wear debris from being dispersed.